The Tall Blacks will not face Kevin Durant at the upcoming basketball World Cup in Spain, after Steven Adams' superstar Oklahoma City Thunder team-mate today withdrew from the USA side.

USA Basketball today announced that Durant, who would have been the best player on the unbackable favourite defending champions, had informed them he was withdrawing from the team, citing tiredness from the draining NBA season.

''Kevin reached out to Coach K (Mike Krzyzewski) and myself this afternoon and expressed that he is just physically and mentally drained from the NBA season and his attention to his many responsibilities,'' USA Basketball National Team Managing Director Jerry Colangelo said today.

''He tried to give it a go at our recent Las Vegas training camp but felt coming out of camp that he was not prepared to fulfil the commitment he made to the team.''

Durant said it had been a difficult decision to make after being a fixture of the side in recent global tournaments.

''I take great pride in representing our country,'' he said.

''[But] I know that I owe it to my USA Basketball team-mates to be totally invested in the experience. After going through training camp, I realised I could not fulfil my responsibilities to the team from both a time and energy standpoint.

''I need to take a step back and take some time away, both mentally and physically, in order to prepare for the upcoming NBA season.''

Durant's sudden withdrawal comes just days after a horrific broken leg suffered by Indiana Pacers star Paul George in a scrimmage at the camp in Las Vegas.

George's season-ending injury has prompted a number of high-ranking NBA people to question whether their players should be participating in international competition.

Dallas Mavericks owner Mark Cuban has been particularly critical of the game's international bodies profiting off the presence of highly paid NBA superstars.

Durant's defection is a good news-bad news scenario for Nenad Vucinic's New Zealand men's team who are in the same pool as the Americans, based in the northern Spanish city of Bilbao.

The Tall Blacks would have relished the chance to match up against the man rated the second best player on the planet, behind only new Cleveland Cavaliers star LeBron James.

The chance to go head to head against a global superstar of his status would have been considered a career highlight by many of the New Zealand players.

But Durant's absence has to weaken the USA side, and give the Tall Blacks a glimmer of hope they can at least be competitive with the Americans.

The USA will still call on a host of franchise-level NBA players, including Derrick Rose, Stephen Curry, Kyrie Irving, James Harden and Anthony Davis, and will still be considered a lock to defend their title in Spain.

But there's no one in the game, James included, with the package of offensive skills that the NBA's leading scorer from last season possesses in his arsenal. Durant's absence will be keenly felt in Spain at a time when the World Cup needs all the big names it can get.

Adams also decided to make himself unavailable for the New Zealand team, citing a desire to continue to work on his game with the Thunder ahead of his second NBA season.

That's proven a costly defection for Vucinic's side which is also without injured regular starting centre Alex Pledger who is unlikely to make the Spain tournament because of a major foot problem.

The World Cup, featuring 24 national teams, takes place from August 30 to September 14 in Spain. The USA is in Group C in Bilbao alongside New Zealand, the Dominican Republic, Finland, Turkey and Ukraine.

The USA opens its tournament campaign on August 30 against Finland, and then faces Turkey on August 31, New Zealand on September 2, the Dominican Republic on September 3, and the Ukraine on September 4.

The top four teams in each pool will go forward to the first round of knockout play.